Granular cell tumor of the male breast: report of a case.

We treated a 35-year-old male with a granular cell tumor in the right breast. Physical examination revealed a solid, flattened, round 3.2 x 2.5-cm mass with an irregular surface, covering skin fixation and right axillary lymphadenopathy. Mammography revealed a well-demarcated high-density mass with a minimal starburst appearance. Ultrasonography revealed a hypoechoic, nonhomogeneous mass with an acoustic shadow. Several enlarged lymph nodes in the right axilla were removed at the time of breast tumor excision. Histologically, the tumor featured nests of round or polygonal cells with abundant eosinophilic cytoplasmic granules and small round nuclei, and the enlarged lymph nodes in the right axilla exhibited no metastasis. Immunohistochemically, there was positive staining for S-100 protein, neuron-specific enolase, and vimentin. The tumor also stained for macrophage CD-68, alpha1-antichymotrypsin, and myoglobin. These immunohistochemical findings suggested the tumor cells to be undifferentiated mesenchymal cells which demonstrated the properties of neurogenic cells and histiocytes.